Mullite ceramics are well known as materials with a high temperature stability, strength and creep resistance. In this research, the effect of a modification with magnesia-stabilized zirconia and yttria-stabilized zirconia, separately, as well as in a mixture with WO₃, in 1:1 and 1:2 ratios on the thermal properties of porous mullite ceramics was investigated. The porous mullite-containing ceramics were prepared by a slip casting of the concentrated slurry of raw materials with the addition of a suspension of Al paste for the pore formation due to the H₂ evolution as a result of the reaction of Al with water. The formed samples were sintered at 1600 °C and the holding time was 1 h. The materials were characterized using X-ray diffractometry, scanning electron microscopy, mercury porosimetry, the laser flash contactless method, thermal shock resistance testing and the non-destructive impulse excitation method for determining the elasticity modulus. The modification of the porous mullite ceramic with a mixture of ZrO₂ and WO₃ oxides had a positive effect by decreasing the thermal conductivity, due to the increased porosity, in comparison to the undoped samples and samples with only ZrO₂. The doubling of the WO₃ amount in the modifying oxide mixtures improved the ceramic thermal shock resistance. The porous mullite ceramics which were modified with magnesia-stabilized zirconia (2.8 mol% MgO) and WO₃ had a lower thermal conductivity and improved thermal shock resistance than the samples with yttria-stabilized zirconia (8 mol% Y₂O₃) and WO₃.

This article discusses an effective method for obtaining superconducting composites based on Y₁Ba₂Cu₃O_7-δ (YBCO) by optimizing the total preparation time in comparison with similar scientific works while searching for effective modifying micro-additives. YBCO-based composites were doped with microparticles of aluminum, nickel, and iron. It was established that the initial ratio of green components, heat treatment, and holding time directly affect the qualitative and quantitative formation of the useful superconducting phase Y₁₂₃, which in turn affects the basic superconducting properties of the final material.

Magnesium diboride can be synthesized under argon ambient, elevated or high pressures. High-pressure syntheses are promising methods for manufacturing of the bulk MgB2 superconductor material. We have been used high pressure of Ar gas in order to investigate its effect on properties of MgB2 superconductor such as critical temperature and current density. Bulk MgB2 superconductor was synthesized from elemental Mg–B powders in thermal explosion mode of self-propagating hightemperature synthesis (SHS) under argon pressure of 25 atm. XRD pattern of the as-synthesized product indicates an almost complete conversion of the reactants to the MgB2 single phase. Most of the diffractions peaks are related to the MgB2 polycrystalline bulk material. The impurity fraction is less than 24.3% in total sample and identified as MgO and MgB4 secondary phases. The positive effect of pressure of Ar gas during synthesis of MgB2 on critical current density JC has been confirmed. The critical current density of the sample was achieved in high pressure reactor was 3.8×106 A/cm2. A superconducting volume fraction of 16% under a magnetic field of 10 Oe was obtained at 5 K, indicating that the superconductivity was bulk in nature. The succeeded level of superconductor parameters of the highpressure synthesized MgB2 and the possibility to produce a large bulk products make this technology very promising for practical applications.

Synthesis of the magnesium diboride doped by microparticles of barium oxide (MgB₂@BaO) composites using a solid-state reaction method has been described. The proposed method gives the possibility to enhance the critical current density of the investigated samples at low temperature in the inert atmosphere. The superconducting parameters (T_c and J_c) have been measured. The influence of the doping agents on superconducting parameters of MgB₂ has been analyzed. Obtained results revealed that the best optimal parameters are for 0.7MgB₂@BaO sample that shows the highest critical transition temperature 39.3 K and critical current density 1.7*10⁶ A/cm². It was found that an increasing BaO content leads to the formation of a useful phase of BaB₆, which demonstrates positive effects on the superconducting properties, acting as the effective pinning centers.